A Japanese volcano has erupted in spectacular fashion, causing authorities to create a 2km no-go zone in the area as molten rock, smoke, ash and lightning crackled and roared through the atmosphere.

No injuries were reported when Sakurajima, on Japan's Kyushu island in the Pacific "Ring of Fire", blew its top earlier this week, with officials saying the display, while impressive, was the result of a relatively average eruption.

"I don’t think there will be any serious impact from the explosion," Kazuhiro Ishihara, a volcanologist at Kyoto University, told NHK.

"But of course we must keep monitoring the volcanic activity."

The explosion and its 2.2km high ash cloud, which generated apocalyptic-looking tongues of lightning, was enough for officials to call a level-three alert, restricting access to the mountain; locals and visitors have also been warned to keep an eye out for cinders and lava flows.

Sakurajima is a highly active volcano, with some 700 eruptions last year, the most having occurred in September last year.